HLEN command is used to get the number of fields in a hash. In Go, it's often used when you want to find out the size of the hash stored in Redis. This can be useful in scenarios like monitoring and limiting the size of hashes, checking if a hash has any keys before performing bulk operations, or controlling flow logic based on hash sizes.
Here is an example of using HLEN in Golang with go-redis, a popular Redis client for Golang:
In this program, we first establish a connection to the Redis server running on localhost at port 6379. We then set a field in a hash named "myhash". After that, we use
rdb.HLen(ctx, "myhash") to get the length of the hash and print it out.
HLen()command. It will help you catch issues like non-existent hash keys, connection issues etc.
HLen()will return 0 for non-existing keys: In reality, Redis treats non-existing keys as empty hashes, so
HLen()command on a non-existing key will not throw an error but will return 0.
Q: What happens if the provided key is not a hash?
A: If the provided key exists in Redis but is not a hash, the HLen command will return an error.
HLen() modify the hash anyway?
HLen() is a read-only operation and does not modify the hash.